The purpose of the proposed research is to further isolate and characterize those antigens shared between adult Schistosoma mansoni and its intermediate host, Biomphalaria pfeifferi. The antigens will be isolated by means of affinity chromatography, and characterized by standard biochemical procedures. Isolated, purified antigens will be tested for their potentials as immunodiagnostic reagents by a labeled latex bead procedure, by ELISA, and by RIA. The antigens will be further tested in mice and hamsters for their potentials as a vaccine against schistosomiasis.